Rocuronium = Vecuronium

[powermd]

Are these essentially the same drug, only with different dosing recommendations for intubation?

If you gave 0.6-1mg/kg vecuronium, would you achieve intubating conditions in a similar timeframe as if you had given the same dosage of rocuronium?

One attending brought up this concept a while back, suggesting that the reason for roc's more rapid onset of action is simply that more molecules are injected faster due to the higher dosing schedule.

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[IceDoc]

Compare the two by using them as a defasiculating dose.
Roc works quickly and reliably.
Vec takes much more time and is unreliable. They are not the same.

You could also follow the ER literature and give Vec 30mg as a rapid sequence intubating dose. Of course, you then have to deal with the consequences.

 

[SleepIsGood]

Compare the two by using them as a defasiculating dose.
Roc works quickly and reliably.
Vec takes much more time and is unreliable. They are not the same.

You could also follow the ER literature and give Vec 30mg as a rapid sequence intubating dose. Of course, you then have to deal with the consequences.

LOL...you have this problem at your institution too huh?

They do the same thing, at my place, and then panic and hope that we can intubate the patient.

 

[periopdoc]

Are these essentially the same drug, only with different dosing recommendations for intubation?

If you gave 0.6-1mg/kg vecuronium, would you achieve intubating conditions in a similar timeframe as if you had given the same dosage of rocuronium?

One attending brought up this concept a while back, suggesting that the reason for roc's more rapid onset of action is simply that more molecules are injected faster due to the higher dosing schedule.

If you mean do they have the same chemical structure and the only difference is labeling, then of course the answer is no. Both are aminosteroid molecules which act by competing for cholinergic receptors on the motor end plate. While they share structural similarities with all of the aminosteroid molecules, they do have a different chemical structure.

Rocuronium Structure - Molecular weight 609.7

Vecuronium Structure - Molecular weight 637.74

Pancuronium Structure - Molecular weight 732.68


But I don't think that is what you are suggesting. You asked, are they ESSENTIALLY the same drug, and the faster action of rocuronium is only because you are giving more molecules of it. That is an interesting question. Since they have different molecular weights, one mg of rocuronium will contain more molecules than a mg of vecuronium. In fact if we look at a 1mg/kg dose of the following drugs in a typical 100 kg individual we will find they include the following number of molecules


Rocuronium 1.64 x 10^-4 moles
Vecuronium 1.56 x 10^-4 moles
Pancuronium 1.36 x 10^-4 moles


Or we could calculate backwards and say how many mg/kg of vecuronium would give you the same number of molecules as a mg/kg of rocuronium in a typical 100 kg man?


1 mg/kg rocuronium would equal
1.05 mg/kg of vecuronium or
1.2 mg/kg pancuronium


Anybody want to experiment with those doses and find out if they give the same time to onset as the mg/kg rocuronium dose? There are a few studies that have compared time to onset of ED95 doses of neuromuscular blockers expressed in micromoles per kg. Since the ED95 dose for vecuronium is 0.045 mg/kg and the ED95 dose for rocuronium is 0.35 mg/kg you end up giving 7.06 x10^-3 moles of vecuronium and 5.74 x10^-2 moles of rocuronium to a typical 100 kg individual. A 10 fold difference and the results are not surprising.

I haven't seen a study that directly compared time to onset of equivalent micromole/kg doses but I will look around a little more.

- pod

 

[jwk]

Are these essentially the same drug, only with different dosing recommendations for intubation?

If you gave 0.6-1mg/kg vecuronium, would you achieve intubating conditions in a similar timeframe as if you had given the same dosage of rocuronium?

One attending brought up this concept a while back, suggesting that the reason for roc's more rapid onset of action is simply that more molecules are injected faster due to the higher dosing schedule.

I guess this is good for mental masturbation, but clinically absurd.

Do y'all actually wait whatever time it says to wait in the package insert and/or use a nerve stimulator to tell if it's worked yet? (also mental masturbation IMHO)

 

[Planktonmd]

Vecuronium and Rocuronium are very similar from a clinical point of view and actually vecuronium produces a more profound blockade that lasts longer at a comparable onset time if you use equipotent doses to Rocuronium.
Roc is newer and has a much more aggressive marketing behind it and that's why many of the new guys think it is a better agent.
And as JWK said we almost never wait for any of these agents to actually work anyway in RSI and I guarantee you that 90% of RSI's are basically done before any meaningful muscle relaxation takes place.

 

[Planktonmd]

and I guarantee you that 90% of RSI's are basically done before any meaningful muscle relaxation takes place.

I should have added: unless you are using good old SUX.

 

[coprolalia]

Vecuronium and Rocuronium are very similar from a clinical point of view and actually vecuronium produces a more profound blockade that lasts longer at a comparable onset time if you use equipotent doses to Rocuronium.
Roc is newer and has a much more aggressive marketing behind it and that's why many of the new guys think it is a better agent.
And as JWK said we almost never wait for any of these agents to actually work anyway in RSI and I guarantee you that 90% of RSI's are basically done before any meaningful muscle relaxation takes place.

-copro

 

[gasspasser]

I'll echo what PlanktonMD and everyone else has said. I think Vec and Roc have very similar onset times, but vec lasts longer or at least is less variable than roc in terms of length of relaxation. All in my clinical experience, of course.

But if you want to look at total intraoperative time utilization (which is what really matters), Rocuronium has a much faster time-to-clinical-effect from anesthesia-start-time because I don't have to reconstitute the darn drug from powder.

 

[coprolalia]

I'll echo what PlanktonMD and everyone else has said. I think Vec and Roc have very similar onset times, but vec lasts longer or at least is less variable than roc in terms of length of relaxation. All in my clinical experience, of course.

But if you want to look at total intraoperative time utilization (which is what really matters), Rocuronium has a much faster time-to-clinical-effect from anesthesia-start-time because I don't have to reconstitute the darn drug from powder.

Probably the biggest selling and utilization point for roc.

-copro

 

[ProRealDoc]

so the question based on the information provided is would any of you use vecuronium for RSI?

 

[Licoricestick]

so the question based on the information provided is would any of you use vecuronium for RSI?

I have used it when working with a consultant who likes to do his RSIs using vec (he's one who doesn't get hung up on mg/kg doses so pretty much every adult gets 8mg) - given first, then prop, tube. However, anyone who is actively vomiting or has somehow earnt themselves a for real RSI (ie the post tonsillectomy bleed we did the other week) rather than perhaps a dogma one gets sux.

Oddly enough I'm definitely not going to use it as a plan in my exam....because you know what the next question will be "So, you've given vec but now a raving lunatic has pulled your drip out before you've given the propofol. What now?"

 

[Licoricestick]

And as JWK said we almost never wait for any of these agents to actually work anyway in RSI and I guarantee you that 90% of RSI's are basically done before any meaningful muscle relaxation takes place.

I don't know.... I find propofol to be a rather good muscle "relaxant"

 

[huktonfonix]

[QUOTE "So, you've given vec but now a raving lunatic has pulled your drip out before you've given the propofol. What now?" [/QUOTE]

I fail to see the problem. The vec is in. laugh at him as he weakens and tell him not to do stupid crap like pulling out his IV. Intubate, start another IV. Ok fine, I guess you could use inhalational agent if you're feeling generous.

 

[Apollyon]

You could also follow the ER literature and give Vec 30mg as a rapid sequence intubating dose. Of course, you then have to deal with the consequences.

Hmm...so when I give 10mg and get the tube in, I don't know what is going on.

And I finally met one of the anesthesiologists here, when he asked two of us about the closed head injury paradigm for his 12 year old son, who had fallen off his skateboard backwards and been knocked out. Otherwise, it is the general surgery people in the trauma bay calling for the gas guys (and they get the attending - no CRNAs for trauma in the uni hospital).

I used to go with roc all the time when sux was not indicated, and then, just recently, had to start going with vec, 'cause that's all there is now.

 

[Licoricestick]

[QUOTE "So, you've given vec but now a raving lunatic has pulled your drip out before you've given the propofol. What now?"

I fail to see the problem. The vec is in. laugh at him as he weakens and tell him not to do stupid crap like pulling out his IV. Intubate, start another IV. Ok fine, I guess you could use inhalational agent if you're feeling generous.[/quote]


I never said the raving lunatic was the patient...plenty of opportunities for people to do stupid things in theatre...

In the exam situation say you pick gas induction - well, it's not really an RSI so the next thing the examiners say is "Now he's aspirated" and they run the scenario from there.

Alternatively you decide to just tube. So the examiners say "Several weeks later you get a letter from a lawyer requesting that you explain yourself in court as to why you paralysed and intubated an awake patient?"

My point was that it works for my boss, and I'm happy to go with his plan when I'm working with him...but as an EXAM answer it's fraught with problems.

 

[Idiopathic]

You could also follow the ER literature and give Vec 30mg as a rapid sequence intubating dose. Of course, you then have to deal with the consequences.

One of the reasons I hate to rely on roc as a RSI med is the false sense of security. what are the consequences specific to high dose vec that arent also attributed to high dose roc? if you are speaking about high dose nondepolarizers in general then obviously i udnerstand your point.